Miniature Coaxial Cable Assembly

Abstract

The present invention relates to a miniature flexible coaxial cable assembly and a method of fabricating the same wherein a plurality of continuous, individually sheath dielectric covered coaxial cable center conductors are located in parallel spaced relationship with their longitudinal axes substantially coplanar. A plurality of continuous drain wires are distributed among the center conductors with their longitudinal axes being coplanar, but offset from the coplanar center conductor longitudinal axes. The center conductors and drain wires are sandwiched between ribbons of conductive foil which are provided thereover with a continuously applied layer of insulation material. The assembly is then bonded along a plurality of lines of contact extending longitudinally of the continuous wires. If the insulation layer is applied by continuous extrusion, such bonding will additionally result in a protective jacket for the assembly.

Parent Case Text

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation application of application, Ser. No. 106,468, filed Jan. 14, 1971 now abandoned.

Description

FIELD OF THE INVENTION

The present invention relates to a flexible coaxial cable assembly including a plurality of coaxial cables having a common ground and provided with individual drain wires, which assembly may be miniaturized and the coaxial cables located on precisely located center spacings.

BACKGROUND OF THE PRIOR ART

There has been a long existing need in the prior art for miniaturized coaxial cables on precisely located center spacings. Due to a requirement for miniaturization, difficulty is experienced in stripping the coaxial cables of surrounding insulation and outer conductor material. It is often desired to associate a separate drain wire with a miniature coaxial conductor, with the result that difficulty in stripping the coaxial conductor is further aggravated by a need for searching for the end of the drain wire before stripping it of insulation.

SUMMARY OF THE INVENTION

The present invention alleviates the difficulties present in the prior art and provides a miniaturized, flexible coaxial cable assembly which is readily stripped of surrounding insulation and outer conductor material. The assembly according to the invention is further provided with a plurality of individual drain wires which are easily located in the assembly and are readily stripped of insulation. The assembly according to the invention is advantageously fabricated by a continuous process wherein the coaxial conductors and drain wires are sandwiched between layers of a conductive foil and, either simultaneously, or subsequently provided thereover with a continuously applied layer of insulation material. The assembly is bonded together by a continuous process along selected lines of contact extending longitudinally of the parallel center conductors and drain wires. The foil layers advantageously provide a common potential conductive shielding for the coaxial cables in the assembly.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide a flexible assembly of coaxial conductors on precisely located center spacings with unshielded drain wires associated therewith.

Another object of the present invention is to provide an article of continuous manufacture including precision spaced coaxial conductors provided with a common potential shielding.

A further object of the present invention is to provide a miniaturized coaxial cable assembly utilizing a plurality of coaxial conductors and unshielded drain wires.

A further object of the invention is to provide a cable assembly of a plurality of coaxial conductors having a plurality of drain wires, located adjacent to a surface of the assembly and relatively recessed with respect to an opposed surface of the assembly.

Still another object of the present invention is to provide a coaxial cable assembly including a plurality of coaxial conductors and drain wires, all precisely spaced and located in the assembly and readily stripped of insulation material.

Still a further object of the invention is to provide a coaxial cable assembly with a plurality of coaxial conductors sandwiched between conductive layers and insulation layers which are bonded along lines of contact located between adjacent coaxial conductors and adjacent the locations of drain wires in the assembly.

Other objects and many attendant advantages of the present invention will become apparent upon perusal of the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective illustrating the method of assembling a coaxial cable assembly according to the present invention;

FIG. 2 is an enlarged detail cross section of a preferred embodiment of a coaxial cable assembly according to the present invention;

FIG. 3 is an enlarged fragmentary detail cross section of a modification of the preferred embodiment shown in FIG. 2, and further illustrating the coaxial cable assembly prior to application of outer insulation layers thereon; and

FIG. 4 is an enlarged detail fragmentary cross section of the preferred embodiment illustrated in FIG. 3, provided thereover with layers of one selected type of insulation material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With more particular reference to FIG. 2 of the drawing, there is illustrated generally at 1, a coaxial cable assembly including a plurality of parallel spaced coaxial cable center conductors 2, 4, 6, 8, 10 and 12, each individually surrounded by a continuous cylindrical dielectric sheath 14. Any desired plurality of conductors may be provided, even though six are illustrated in detail. The assembly 1 also includes a plurality of parallel spaced conductors or drain wires 16, 18, 20 and 22. The drain wires are selectively distributed among the adjacent spaced coaxial conductors 2-12, and are of circular cross section. However, the drain wires 16-22 may be of any desired cross section configuration.

As shown in FIG. 2, the drain wire 16 is selectively provided between the spaced pair of coaxial conductors 2 and 4. The drain wire 18 is selectively disposed between the spaced coaxial conductors 6 and 8. The drain wire 20 is disposed adjacent to the single coaxial conductor 10. The drain wire 22 is disposed adjacent to the single coaxial cable conductor 12. Thus, the drain wires may be selectively distributed between adjacent pairs of coaxial conductors or associated with but a single coaxial conductor. Additionally, no drain wire is shown between the spaced coaxial conductors 4 and 6. Thus, any desired distribution of the drain wires may be effected without departing from the scope of the invention. The center conductors 2-12 and the distributed drain wires are sandwiched between layers 24 and 26, respectively, of a conductive material, such as metal foil in continuous ribbon configurations. To complete the assembly, the foil layers 24 and 26 are respectively provided thereover with layers 28 and 30 of an electrical insulation material which may also be of continuous ribbon configurations. The conductive foil layers 24 and 26 provide a common electrical shielding for all of the coaxial conductors within the assembly, and the insulation layers 28 and 30 electrically insulate the assembly. As shown in the assembly, the longitudinal axes of the coaxial cables are coplanar and positioned on precisely located center spacings. The longitudinal axes of the drain wires within the assembly are also coplanar but offset from the coplanar axes of the center conductors. The layers 26 and 30 of the assembly are provided with alternate raised portions overlying the center conductors and recessed portion 32 overlying each of the distributed drain wires, with the conductive layer 26 contacting each drain wire along a line of contact extending longitudinally of each drain wire. Thus the layers 26 and 30 provide one surface of the assembly with corrugations formed by the raised and recessed portions 32. The layers 24 and 28 comprise an opposed surface of the assembly with the conductive layer 24 contacting each of the distributed drain wires along a line of contact extending longitudinally of each drain wire. In the resultant assembly, the drain wires are substantially recessed with respect to the surface formed by the layers 26 and 30, and are located substantially adjacent to the opposed surface formed by the layers 24 and 28.

To complete the assembly, the layers 26, 30, 24 and 28 are bonded together at their respective longitudinal side margins 34 and 36 along a continuous line of mutual contact. Additionally, the layers 30 and 34 are bonded to each of the drain wires along a line of contact 38 extending longitudinally of each drain wire. The layers 24 and 28 are bonded to each drain wire along a line of contact 40 along the longitudinal axis of each of the distributed drain wires. Additionally, the layers 26 and 30 are bonded to the layers 24 and 28 along lines of contact 42 and 44 between adjacent coaxial conductors where no drain wire is provided. Bonding along such lines of contact is accomplished by ultrasonic welding techniques, for example. However, it should be understood that other bonding techniques may be utilized. The completed assembly comprises a plurality of precisely spaced coaxial connectors with distributed drain wires precisely located substantially adjacent one surface of the assembly. The locations of the center conductors and drain wires are thus predictable. Since bonding of the assembly is limited to selected lines of contact, the insulation and conductive layers are easily stripped from the coaxial conductors and the drain wires. With center conductors and the drain wires predictably located in the assembly, they are easily found in the assembly and stripped of the layers 24, 26, 28 and 30. If desired, the insulation layers 28 and 30 may be first provided with the conductive layers 26 and 26 as a coating thereon prior to incorporation into the assembly shown in FIG. 2. Alternatively, the conductive and insulation layers may comprise separate ribbons sequentially bonded to the assembly as described.

In the assembly of the FIG. 2 embodiment, reference will be made to FIGS. 1 and 2. The former figure shows the center conductors with their outer sheaths 14 and the distributed drain wires, one of which is shown at 16, of continuous longitudinal configurations and maintained on precisely located center spacings. Continuous ribbons 24 and 26 of a conductive material is provided over the assembly. Outer layers 28 and 30 of electrical insulation material is provided over the ribbons 24 and 26. The completed assembly is then passed between a pair of cooperating ultrasonic welding dies, schematically illustrated at 45. The dies 45 weld the layers 24, 26, 28 and 30 along the continuous lines of contact described with respect to the FIG. 2 embodiment. Alternatively, the conductive layers 24 and 26 may be first bonded along the continuous lines of contact, with the insulating layers 28 and 30 sequentially provided over and subsequently bonded to the layers 24 and 26 along the lines of continuous contact. Such can be accomplished by a single pass through sequential pairs of welding dies similar to the dies 45. In still another modification, the conductive layers 24 and 26 may comprise conductive layers already connected to the insulating layers 28 and 30 prior to being bonded to the FIG. 2 assembly.

FIG. 3 illustrates another preferred embodiment of the invention. With reference to the figure, a subassembly comprising plurality of spaced exemplary coaxial conductors 46 are provided thereover with an individual sheath 48 of dielectric material. As in the embodiment of FIG. 2, the conductors and associated dielectric sheaths are of continuous parallel configuration with the longitudinal centerlines of the coaxial conductors 46 being coplanar. Distributed among the coaxial conductors 46 are a plurality of conductors or drain wires 50. As in the embodiment of FIG. 2, the drain wires may be of circular or rectangular or any other desired configuration. In each of the embodiments of FIGS. 2 and 3, the coaxial cable center conductors 2, 4, 6, 8, 10, 12 and 46 are positioned in their respective assemblies on precisely located center spacings. As shown in FIG. 3, a drain wire 52 may be selectively substituted for a normally occurring coaxial cable center conductor 46. Accordingly, the longitudinal axis of the drain wire 52 is located on a center spacing between the precisely center spaced adjacent coaxial conductors 46. As shown in FIG. 3, the longitudinal axes of the center conductors 46 are coplanar. The longitudinal axis of the drain wires 50 and 52 are also co-planar but offset from the longitudinal axes of the center conductors 46. As above described with reference to the embodiment of FIG. 2, in similar fashion the drain wires 50 may be selectively distributed among the spaced center conductors 46 and associated with either a single or a pair of such center conductors as described.

A top layer of conductive metal foil 54 is provided over the center conductors and drain wires and is provided with generally recessed planar portions 56 overlying and covering each of the drain wires 50 and 52. The layer 54 also includes lateral side margins, one of which is shown at 58. The assembly is further provided with a bottom conductive layer 60 of foil or other suitable material having recess portions 62 on each side of every drain wire 50 and 52. Such recess portions 62 abut against the recessed portions 56 of the layer 54 along lines of contact extending parallel to the longitudinal axes of the drain wires and center conductors. The layer 60 is further provided with lateral side margins, one of which is shown at 64, abutting a respective side margin 58 along lines of mutual contact extending parallel to the drain wires and center conductors of the FIG. 3 embodiment. Along such lines of contact the layers 54 and 60 are bonded together, for example, by ultrasonic welding or other suitable techniques.

The subassembly of FIG. 3 is especially suited for continuous fabrication according to the schematically illustrated process shown in FIG. 1. More particularly the center conductors 46 and the drain wires 50 and 52 may be of continuous longitudinal configuration and suitably maintained in place according to their desired center spacings. Welding along the described lines of contact may then be accomplished by passing the subassembly continuously through a pair of ultrasonic welding dies such as the dies 45 of FIG. 1.

The FIG. 3 subassembly may then be provided thereover with conductive layers similar to the layers 28 and 30 of the embodiment illustrated in FIG. 2. More particularly, such layers 28 and 30 are placed in overlying relationship on the conductive layers 60 and 54 and the subassembly is again passed through the same welding dies, thus bonding the layers 28 and 30 along the identical lines of contact adjacent each of the drain wires 50 and 52.

With reference to FIG. 4, an alternative insulation technique for the FIG. 3 subassembly is illustrated. In FIG. 4, an outer jacket 66 encapsulates the subassembly of FIG. 3, and is applied by a molding or continuous extrusion process. As shown, the jacket is provided with a planar surface 68 and projecting portions 70 covering the dielectric sheathed center conductors 46. For ease in fabrication, a raised portion 70 is provided at each expected center space location of a sheathed center conductor 46. Accordingly, where a drain wire 52 is substituted for a normally located center conductor 46, the corresponding raised portion 70 will include a relatively massive application of insulating material advantageously applied automatically during the molding or extrusion process.

Other modifications and embodiments of the invention are to be covered by the scope of the appended claims.

For example, FIG. 5 is a fragmentary enlarged cross section of yet another embodiment according to the present invention. With reference to FIG. 5, a pair of parallel elongated generally cylindrical dielectric sheaths 72 each having a center conductor 74 of a coaxial cable, are similar to the dielectrics 14 and 48 of the previously described embodiments. Each dielectric sheath 72 has associated therewith an elongated ground wire conductor, 76, similar to the ground wire conductors 16 or 58 of the previous embodiments. A sheath of relatively thin electrically conducting foil 78 is generally of tubular construction and encircles each dielectric sheath 72 and its adjacent ground conductor 76 along their entire elongated lengths thereof. For example, as in the previously described embodiments, the embodiment shown in FIG. 5 may be modified by eliminating any desired ground conductor 76, in which case, the tubular foil 78 will encircle only the remaining dielectric 72. To complete the subassembly, the pair of foil encircled dielectric sheaths 72 are located in adjacent relationship and provided thereover with a molded or extruded dielectric layer 80 similar to the layer 70 described in conjunction with FIG. 4.

In accordance with the objects of the present invention, which objects are applicable to all the embodiments described herein, each ground wire conductor, such as the conductor 76, is precisely located with respect to a corresponding dielectric sheath 72 within the outer surrounding dielectric insulation layer, such as the layer 80. None of the ground wire conductors are, for example, spirally wrapped about a corresponding dielectric sheath. This is highly advantageous, since upon stripping the outer insulation sheath from the assembly, each ground conductor is precisely located within an assembly, with each dielectric sheath and its corresponding center conductor being exposed in precisely located and predictable positions, thereby enabling termination thereof to a standard connector block, not shown. Thus, according to the present invention, none of the exposed ground wire conductors or center conductors need be reoriented before they are terminated to a standard connector block.

Another object of the present invention is to provide a coaxial cable assembly including a plurality of coaxial conductors and drain wires precisely spaced and located in a common outer insulation layer, with the insulation layer provided with lateral margins that may be joined to an adjacent margin provided on an outer insulation layer of another similar coaxial cable assembly.

As shown in FIG. 5, the surrounding insulation layer 80 is provided with a first lateral margin and a second lateral margin 82 and 84, respectively. Another surrounding insulation layer 86, of another coaxial cable assembly provided with at least one dielectric sheath 72 encircling a center conductor 74 and surrounded by an encircling tubular foil layer 78, includes a lateral margin 88 which may be placed in adjacent relationship with respect to the margin 82. According to the features attributable to the present invention, the adjacent insulation layers 80 and 86 may be advantageously terminated to a common connector block, not shown, the fabrication technique of the present invention enabling all the center conductors 74 and the associated drain wires 76 to be precisely located in the assembly so as to eliminate the need for reorienting the conductors before termination to the common connector block. If desired, the margins 82 and 88 may be secured together by an adhesive or by heat sealing, for example. It should be understood that the insulation layers 80 and 86 may assume many different configurations and that if provided with lateral margins such as the margins 82, 84 and 88 such configurations may be placed in adjacent relationship to provide any desired number of center conductors 74 or drain wires 76.

Claims

What is claimed is:

1. A coaxial cable assembly, comprising:

a. first and second conductive layers in continuous longitudinal configurations;

b. a plurality of parallel spaced center conductors, each of said center conductors individually provided thereover with a dielectric sheath;

c. a plurality of drain wires selectively distributed among said spaced center conductors;

d. the longitudinal axis of said center conductors being coplanar;

e. the longitudinal axis of said drain wires being coplanar;

f. said center conductors and said drain wires being disposed between said first and said second conductive layers with said drain wires being bonded thereto along lines of contact; and

g. insulation material overlying each of said conductive layers.

2. The structure as recited in claim 1, wherein, said drain wires are parallel and positioned between adjacent pairs of center conductors.

3. The structure as recited in claim 1, wherein, the longitudinal axes of said center conductors are located on predictable center spacings.

4. The structure as recited in claim 1, wherein, said drain wire longitudinal axes are straight.

5. The structure as recited in claim 1, wherein, said longitudinal axes of said drain wires are coplanar and located offset with respect to the coplanar axes of said center conductors.

6. The structure as recited in claim 1, wherein, said drain wires are recessed with respect to one surface of said assembly and are located adjacent to an opposed surface of said assembly.

7. The structure as recited in claim 1, wherein said first and second conductive layers abut each other along lines of contact extending parallel to the longitudinal axes of said drain wires.

8. A flat multi-conductor coaxial cable assembly, comprising:

a. a plurality of parallel, spaced center conductors, the longitudinal axes thereof being coplanar, and further each of said center conductors being individually provided thereover with a dielectric sheath;

b. a conductive tubular foil surrounding each of said dielectric sheaths; and

c. a plurality of longitudinally coplanar drain wires each of which extends parallel to each of said center conductors and intimately contacting said foil sheath surrounding said dielectric sheath, further the position of each of said drain wires relative to said center conductor being substantially constant and determinable without cutting into said flat multiconductor coaxial cable.